The present invention relates to apparatus and methods for manufacturing electrical phase insulators for dynamoelectric machines.
As is well known in the art, dynamoelectric machine stator assemblies may often comprise a magnetic core having a bore, axially extending slots, and windings which may comprise a plurality of coils formed by multiple turns of wire conductor. The multiple turns have side turn portions which are disposed within the axially extending slots, and end turn portions which project from the slots and which are disposed about end faces of the core. The conductors employed in forming the plurality of coils are provided with an electrically insulating coating to prevent short circuiting between the turns and each slot is electrically insulated from the core by, for example, a slot liner in order to prevent grounding of the windings to the stator core. Because winding to winding voltage potentials can be appreciable, the conductor turns of one winding are often separated or insulated from the conductor turns of another winding by additional insulation. This additional insulation may include insulating wedges or slot separators disposed within the slots of the magnetic core to separate side turn portions of one winding from the side turn portions of another winding. The end turn portions of different windings are often separated from one another by phase insulators disposed about faces of the core and between end turn portions of the different windings.
Insulators for separating end turn portions of different windings or winding phases of dynamoelectric machines such as motors are generally well known in the prior art. For example, Stein U.S. Pat. No. 3,575,623 of Apr. 20, 1971; McNeal U.S. Pat. No. 4,100,005 of July 11, 1978; and Droll United Kingdom U.S. Pat. No. 1,461,126 of Jan. 13, 1977 all illustrate and describe what is referred to herein as phase insulation. Moreover, co-pending application Ser. No. 918,055 which was filed June 22, 1978 in the name of Sammy L. Miller and Alan L. Kindig (entitled: "Methods and Apparatus For Inserting Winding End Turn Phase Insulation") relates to, among other things, utilization of phase insulation. The disclosures of all of these above-mentioned patents and application are incorporated herein by reference.
As discussed in the McNeal and Droll patents, methods utilized in the past in the fabrication of phase insulation have been wasteful of material. One such common method has involved the stamping of phase insulation pieces from a sheet or strip of insulating material. This process has resulted in production of large volumes of scrap, with the amount of scrap being generally proportional to the length of the "connectors" which interconnect generally planar insulation pieces that ultimately are circumferentially disposed in a stator assembly between radially spaced, circumferentially extending end turn portions of two different phase windings. Another problem associated with the more common practice of stamping phase insulation pieces is that different dies must be provided in order to produce insulators that are used with motors having different stack heights. Motor manufacturers typically produce motors having a wide range of stack heights or core lengths, and thus, different phase insulators with varying length connectors must be provided for the motors having different core lengths. The co-pending related Burns application Ser. No. 8,603 discloses, among other things, new approaches to fabricating such stamped phase insulators which substantially reduce the material waste and die inventory problems discussed above. The above-referenced Droll patent and McNeal patent represent another approach for fabricating phase insulators which reduces problems such as material waste and die inventories. With the approach represented by the McNeal and Droll patents, phase insulators are fabricated from different strips or bands of material as opposed to stamping a phase insulator from a single sheet of material. Thus, material waste and die inventories are substantially reduced with this approach. The above-referenced related Burns application also discloses, among other things, a way of still further reducing the amount of material utilized in producing individual phase insulators.
The above-referenced Miller et al application teaches one approach for automatically placing phase insulation in stator cores; and the above-referenced Droll patent teaches a very different approach for machine placing phase insulation in slots of stator cores. As discussed in the related Burns application, it has been determined that some problems may be encountered due to the inherent nature of insulator pieces that have been available heretofore. More specifically, when insulation pieces manufactured as illustrated in the Droll patent are placed in automatic coil placing equipment, problems arise due to the fact that the connectors of phase insulation fabricated as described by Droll do not become properly positioned in stator slots. In the case of the approach described by Miller et al, difficulties may be encountered in positioning the connectors of phase insulation in slots of insulator placing tooling disclosed by Miller et al. More specifically, when insulators are produced from planar insulation material and filamentary material which typically is supplied in coiled or rolled form, such material tends to have a curvature or "set". This curvature appears to remain and still be present in material even after phase insulators have been formed. However, curvature of the connectors in phase insulation pieces is particularly troublesome when machines are used to automatically place such connectors in long straight slots - whether such slots be the slots of a stator core of slots of an insulator placing apparatus.
The related co-pending Burns application discloses, among other things, new and improved phase insulators characterized by straight filamentary connectors. These phase insulators, with connectors having any curvature or "set" removed therefrom, eliminate problems previously encountered in automatic placement of phase insulators in magnetic cores as previously discussed. Further, the new insulators require less material for fabrication than that previously required by prior known insulators.
Thus, it would be desirable to provide new and improved apparatus and methods for fabricating phase insulator, e.g., insulators disclosed by the co-pending Burns application, or by others.
Accordingly, it is a general object of the present invention to provide new and improved apparatus and methods for fabricating phase insulators.
A more specific object is to provide new and improved apparatus and methods for fabricating insulators having straight connectors of the type disclosed in the previously mentioned Burns application.
More specifically, an object of the present invention is to provide new and improved methods and apparatus for fabricating phase insulators having a connector portion of filamentary material and wherein such insulators may be easily inserted by machine into straight slots of a magnetic core.
Another object of the present invention is to provide new and improved methods and apparatus for fabricating phase insulators which minimize fabrication steps and material handling.
Still another object of the present invention is to provide new and improved methods of fabricating phase insulators from strips of materials of indeterminate length.
A further object of the present invention is to provide new and improved apparatus for moving, manipulating, securing and severing material strips of indeterminate length for establishing phase insulators having a configuration which facilitates subsequent machine placement in a magnetic core.
A still further object of the present invention is to provide new and improved apparatus having means for conditioning at least one strip of material utilized as connectors for phase insulators so as to remove any curvature or "set" therein prior to securing such connectors to planar strips of insulating material for establishing phase insulators.